Nonwoven fabrics are engineered fabrics that provide specific functions such as absorbency, liquid repellence, resilience, stretch, softness, strength, flame retardant protection, easy cleaning, cushioning, filtering, use as a bacterial barrier and sterility. In combination with other materials the materials can provide a spectrum of products with diverse properties, and can be used alone or as components of apparel, home furnishings, health care, engineering, industrial and consumer goods.
Nonwoven fabrics are typically manufactured by combining small fibers in the form of a sheet or web (similar to paper on a paper machine), and then binding the fibers either mechanically (as in the case of felt, by interlocking them with serrated needles such that the inter-fiber friction results in a stronger fabric), with an adhesive, or thermally by applying a binder in the form of powder, paste, or polymer melt and melting the binder onto the web by increasing temperature.
Spunlaid nonwoven fabrics are made in one continuous process. In this process, polymer granules are melted and the molten polymer is extruded through spinnerets. The continuous filaments are cooled and deposited on to a conveyor to form a uniform web. Residual heat can cause filaments to adhere to one another, but is not regarded as the principal method of bonding.
Meltblown nonwoven fabrics are made by extruding low viscosity polymers into a high velocity airstream upon leaving a spinneret which scatters the melt, solidifies it and breaks it up into a fibrous web. Current spunlaid and meltblown systems have a prohibitively high cost, consume large amounts of energy and experience maintenance problems due to nozzles clogging during operation. These system also have lower production rates because they are limited by the volumetric output of grams per hole per minute (throughput rate). Accordingly, a need exists for a low cost, easily maintained system for forming nonwoven fabrics.